Julius e



(No Model.)

J. E. MITCHELL.

LOOK.

NITED STATES PATENT. OFFICE...

JULIUS E. MITOHELLOF ELGIN, ILLINOIS.

LOCK.

SPECIFICATION forming part of Letters Patent No. 532,893, dated January22, 1895.

Application filed January 8,1894. Serial No. 496,072. (No model.)

To all whom it may concern:

Be it known that I, JULIUS E. MITCHELL, of Elgin, in the conntyof Kaneand State of Illinois, have invented certain new and useful Improvementsin Door-Locks; and ldo hereby declare thatthe following is a full,clear, and exact description thereof, reference being had to theaccompanying drawings, and to the letters of reference marked thereon,which form a part of this specification. I

This invention relates to improvements in looks and more particularly inthat class of looks especially designed for use on the doors of housesand other buildings and adapted to be reached with a key from both sidesof the door.

The object of the invention is to provide an improved construction oflock such that while generally similar to the form now in common use,and while equally capable of performing satisfactorily all the functionsthereof, the lock can be readily so adjusted as to render it practicallyimpossible to unlock it from the outside either with a proper key orwith any surreptitious instrument, except by entirely destroying thesurrounding structure.

My invention will be fully understood from the following descriptiontakenin connection with the accompanying drawings, in which Figure 1 isa side elevation, with parts in section, of a lock constructed inaccordance with my invention, the outside Wall of the casing beingremoved. Figs. 2 and 3 are similar views of the locking mechanism,showing the parts in different positions. Figs. 4 and 5 arecross-sections on lines i.4t and 55 of Fig. 1. Fig. 6 is a similar viewon line 6-6 of Fig. 3. Fig. 7 is a detail showing the exteriorappearance of the inside key-hole. Fig. 8 shows one of the lock keys.

A designates the caseof the lock which, in this instance, is a mortiselock, adapted to be inserted in a suitable aperture in the door, afterthe usual manner. Said case is of substantially the ordinaryconstruction, having a removable side wall A adapted to be secured inplace by a suitable screw 0., and in this instance shown as forming thatside of the case designed to be placed adjacent to the outside of thedoor.

13 designates the latching mechanism as a whole, the same being of anydesired or suitable construction and forming no part of my invention. 7

As is usual in looks of this class, the locking bolt as shown comprisesa heavy head or tongue 0, reciprocating through a slot in the face ofthe case, and a thin shank O rigidly secured to the head or tongue 0 andextending nearly the fulllength of the case. Between the shank 0' of thebolt and the rigid side wall A of the case, a tumbler D is pivoted uponalug a projecting from said side wall A near the front thereof. Saidtumbler extends back nearly to the rear wall of the cas and is providedabout midway of its length with a lug d normally resting on the top ofthe bolt shank ,O and adapted to engage either the front or rear edge ofa lug c which projects upward from the edge of said bolt shank. A springE pressing on a lug d of the tumbler near the front end thereof servesto maintain the lug d in contact with the upper edge, of the bolt,except at such times as the tumbler is raised by the key to permitthelug c to pass 5 beneath the lugd in the locking and unlocking of thedevice.

Key-holes a and a are provided in the outer and inner side walls A and Arespectively of the case, but instead of being placed opposite eachother they are separated laterally by a considerable distance, theoutside key-hole a being in this instance locatednear the rear of thecase, while theinside key-hole a is located about midway of the lengthof 8 5 the same. In order to support and afford a bearing for the pointof the stem of the key a bearing aperture a is provided in the "wall ofthe case opposite each of said key-holes, said apertures being as hereinshown extended only partway through the walls, which are thickened intheir adjacent portions, as shown at a By this construction the innerend of the key shankis supported, while at the same time I avoid cuttingthrough the side 5 wall of the lock case, so that said inner end 'of thekey shank never protrudes through the lock case. One advantage of thisconstruction is the avoidance of an aperture at this point through whichdust might Work in to the lock case from the mortise, and furthermorethe key is entirely protected from manipulation by nippers even thoughthe wood-work of the door be cut away as a solid metal wall isinterposed between the key and the exterior of the lock ease. I am awarethat it is not new to provide the wall of a lock case at a pointopposite the key hole with a hole or opening extending through said wallforming a socket in which the inner end of a key shank may enter and besupported, and I therefore make no claim to such a construction. Thebolt shank C and tumbler D are designed to be operated in a usual mannerby a key inserted at either key-hole and tothis end said shank isprovided at a point adjacent to each key hole with the usual V- shapednotch c by engaging which the key acts to shift the bolt, while thetumbler-D extends across said notches in position to be lifted by thekey so as to disengage the lug d from the lug c and permit said bolt tobe so shifted. At a point adjacent to the inside key-hole a however, andin this instance just forward thereof, an oscillating pawl or catch F ispivotally mounted upon a stud (i projecting from the inside of the wallA of the case. The rear end F of the pawl normally stands within reachof the bit or web of the key inserted at a so that by suitably turningthe latter the pawl may be oscillated as desired. The forward end F ofthe pawl is adapted when thrown up to engage the lower edge of the boltshank O and the latter is provided with a rearwardly facing shoulder cbehind which said end F of the pawl may rest when the bolt is thrown outand thereby prevent the return of the bolt until said pawl shall havebeen withdrawn by a key inserted at the inside key-hole a Inasmuch asthe end F of the pawl is liable to be raised when the bolt is drawn in,the lower edge of the shank C is recessed at a just forward of theshoulder c to receive said pawl end (see Fig. 3), the exact shape of therecess being immaterial. A fixed stop a is herein shown as projectingfrom the wall A of the case in po' sition to engage the shoulder a andlimit the inward or rearward movement of the bolt, the lower edge of theshank at the rear of the shoulder being shown cut away to avoidinterference with said stop during the forward movement of the bolt. Byreason of the cut away portion interference with the rear end F of thepawl F when lifted, as shown in Fig. 1, is also avoided.

The pawl F is normally held from movement by a suitable fiat spring Gwhich exerts a constant upward pressure on the under side of the pawl.Said under side of the pawl is shown formed with a central projection fand on opposite sides of the latter with shoulders f and f locatedadjacent to the ends F and F respectively. WVhen the pawl is turned intoa substantially horizontal position (as shown in Fig. 2) the line ofpressure of the spring G on the point of the projection flies directlythrough the center of the pivot a and the pawl is lightly held frommovement in either direction. If however, the pawl is slightly movedfrom this horizontal or central position, the pressure of the springwill continue to turn it in the direction in which it was started untilone of the shoulders f or f comes into contact with said spring, inwhich case one of the ends F or F respectively will have reached itsnormal uppermost position while the other end of the pawl will havereached its lowermost position. In either position the rear end F of thepawl is within range of the bit of the key so as to be moved by the samewhen approached from either above or below, the spring G yielding stillfurther at each end of the throw of the pawl to permit the key to passby its end F (see Fig. 3) and then returning said end into position tobe engaged by the key on its return.

With such construction it is obvious that if the bolt is thrown out bymeans of an inside key and the latter turned to substantially theposition shown in Fig. 3, the forward end F of the pawl will pass behindthe shoulder c and absolutely prevent the bolt from being withdrawn by akey inserted in the outside key-hole. At the same time the action of theinside key will not be interfered with since the reverse movementnecessary to withdraw the bolt will obviously raise the rear end of thepawl and simultaneously lower its front end from engagement with theshoulder 0 If, however, it is desired to lock the door from the insidein such manner as to leave the lock in condition to be opened fromwithout, as for example, by some member of the family or household whois to return later, it is only necessary to turn the key into theposition shown in Fig. 2, which will bring the pawl into its middle orhorizontal position free of engagement with the bolt. Obviously when thepawl is in this position the bolt may be withdrawn by a key inserted ateither the inside or outside key-hole;

Any suitable key K (Fig. 8) may be employed in alock of the characterdescribed and preferably, as herein shown, the same key will be used forthe outside and inside key-hole, though obviously differently shapedkeys might be employed if so desired. In order, however, to enable theposition of the inside key necessary to bring the pawl into its middleor horizontal position, to be determined easily and accurately, Iprovide on the outer edge of the inside key-hole a groove or mark a andon that part of the stern of the key which will come adjacent to saidkey-hole when the the key is inserted, a corresponding mark or groove7a, said groove being so located as to stand exactly opposite eachotherwhen the key is in the position desired. Consequently in order toset the look so as to permit of its being opened from without it is onlyneces sary to turn the inside key until the grooves a and 7c coincide,when the parts within the lock will have been brought into the correctrelation. Said groove a though herein shown for the purpose ofillustration, will obviously be placed upon the case of the lockitselfonly IIO when the latter is a rim or face look. If a mortise lock as inthis instance, such groove will necessarily be placed upon the key-holeescutcheon or adjacent exposed part.

Obviously the distance from the outside key-hole to the pawl F would ofitself render it extremely difficult to operate said pawl by means of alock pick introduced through said key-hole. As a further improvement,however, and in order to render such operation absolutely impossible,that corner of the interior of the case in which the outside keyhole islocated is herein shown separated from the rest of said interior by apartition A extending from the rear to the bottom wall of the case andintegral therewith and with the rigid side wall A Said partition isapertured at a for the passage of the bolt shank C and tumbler D, thatpart of the aperture between the shank O and the outside wall A beingnormally filled by a suitable rib a projecting from said wall A. Theaperture of is made just wide enough to receive the bolt shank O and thetumbler D is made sufficiently narrow at this point to be capable of itsnecessary oscillatory movement. The space above or below the tumbler inthe various positions of the latter is, however, always closed bysegmental spurs d d projecting from the upper and lower edges of thetumbler adjacent to the partition A and in front of the same. By thisconstruction it is obvious that every aperture through which a lock pickintroduced at the outside key-hole might be attempted to be thrust inorder to reach the pawl F is effectually closed at all times, no matterwhat the position of the locking mechanism, so that when said pawl Fisin position to lock the bolt it becomes absolutely impossible towithdraw the bolt except from the inside. The extreme end D of thetumblerD or that portion at the rear of the partition A is herein shownmade of reduced Width in order that breakage may occur back of saidpartition in case undue pressure is brought to bear upon the tumbler byan instrument inserted through the outside key-hole.

In Fig. 2 the pawl F is shown, and I have hereinbefore described it asbeing, in a substantially horizontal position, but this is .forconvenience in drawing only, it being obvious that to throw or lock thebolt by the use of the inside key, and also leave the lock in positionto be unbolted by the outside key, the bit of the inside key (afterperforming its duty of throwing the bolt outward,) will rest between thelower edge of the shank O and the rear end F of the pawl, and that inpractice this pawl will, by reason of the pressure of the spring G,assume the position shown in Fig. 1.

It will of course be understood that for convenience in assembling theparts as well as to lessen the cost of the lock as a whole, certainfixed sizes or standards are in common use in the trade. In thisinstance the lock case shown is of greater interior thickness than thetumbler, and hence that part of the aperture in the partition A which isbetween the shank andthe removable part of the lock case is shown asbeing filled by the projecting lug, but obviously it may be closed by athickening of the shank or tumbler at this point, or

in any other suitable manner.

I claim as my invention 1. An improved lock, comprising an outer caseprovided in its opposite sides with laterally separated key-holes, of abolt mechanism adapted to be operated by a key inserted at eitherkey-hole, and mechanism operated by a key inserted at one key-hole only,adapted to lock the bolt mechanism against withdrawal by a key orinstrument inserted at the other key-hole, substantially as described.

2. An improved lock, comprising a case provided with a key-hole on itsinner side and a second key-hole on its outside, said key-holes beinglaterally separated, of a sliding bolt adapted to be actuated by a keyinserted at either key-hole, and a pivoted pawl adapted to be moved bythe inside key into engagement with the bolt, whereby the latter is heldfrom withdrawal by an outside key, substan tially as set forth.

3. An improvedlock comprising a case provided with a key-hole on itsinside, a second key-hole on its outside laterally separated from thefirst key-hole, a bolt mechanism normally adapted for operation fromeither keyhole, a pivoted pawl near the inside key-hole, adapted foroscillation by the inside key to engage or disengage the bolt, andcorresponding parts or grooves on the key and adjacent portion of thecase or escutcheon, whereby the position of the pawl may be determinedby the coincidence of the grooves, substantially as described.

4. A look comprising a case provided in its inner side with a key-holeand in its outer side with a second key-hole, said key-holes beingout ofline with each other, a bolt mechanism adapted for operation from eitherkeyhole, a pawl operated by the inside key for locking the bolt whenthrown against operation by the outside key, a partition dividing theinterior of the case between the key-holes, said partition beingapertured only for the passage of the bolt mechanism, whereby access tothe pawl through the outside key-hole is entirely prevented,substantially as described.

5. A look comprising a case provided in its inner side with a key-holeand in its outer side with a second key-hole out of line with the insidekey-hole, a bolt mechanism normally adapted for operation from eitherkeyhole, a pawl operated by the inside key for locking the boltmechanism when the latter is thrown against actuation by the outsidekey, and a spring for holding the pawl either at its extreme orintermediate positions, substantially as described.

6. A look comprising a case provided on its opposite sides withkey-holes out of line with each other, a bolt mechanism adapted foroperation from either key-hole, comprising a reciprocatory boltextending past both key-holes and an oscillatory tumbler also extendingpast both key-holes between the bolt and one side of the casing, apivoted pawl operated by the inside key for locking the bolt when thrownagainst actuation by the outside key, a partition dividing the interiorof the case between the key-holes and apertured only for the passage ofthe bolt and tumbler, and segmental spurs on said tumbler adjacent tosaid partition, whereby access to the pawl through the outside key-holeis entirely prevented, substantially as described.

7. Alock having an inside compartment into which the rear end of thebolt and tumbler project through a suitable slot in the front wall ofsaid compartment, arms upon the upper and under side of said tumbler,projecting respectively above and below the ends of the said slot,whereby access to the interior of the look through said compartment isprevented, substantially as described.

8. In a lock having abolt and a tumbler, the

combination of two key-holes in opposite sides thereof and out ofalignment with each other, a spring pressed pivoted pawl injuxtaposition to the inside key hole and to the bolt, whereby said pawlmay be actuated by the key inserted through the inside key-hole toengage a suitable shoulder in the bolt and prevent retraction of thelatter by a key insorted through the outside key-hole, substantially asdescribed.

9. In a lock case having a key-hole in one side, a relatively thickportion on the side of the case opposite said key-hole, and areeess onthe inside of said thickened portion adapted to support the end of thekey when the latter is inserted in the key-hole, substantially asdescribed.

In testimony that I claim the foregoing as my invention I affix mysignature in presence of two witnesses.

TAYLOR E. BROWN, ALBERT I'I. GRAVES.

